Thesis Defense March 6, 2000 Lexical Simplification and Elaboration: An Experiment in Sentence Comprehension and Incidental Vocabulary Acquisition Ken Urano Abstract: Use of simplification and elaboration to enhance input comprehension has attracted attention of SLA researchers. It is commonly believed that simplifying input will enhance L2 comprehension; however, several researchers have argued against its use because (a) simplifying input does not necessarily aid comprehension (e.g., Blau, 1982), and (b) it removes from the input linguistic items that L2 learners need to learn (e.g., Yano, Long, & Ross, 1994). Input elaboration has been proposed as an alternative to simplification under the belief that it aids comprehension but does not hinder language learning. The present study reports on an experiment in the effects of simplification and elaboration on L2 comprehension and SLA with a focus on the lexical domain of English. Forty Japanese learners of English participated in the study, and the results suggest that (a) both lexical simplification and elaboration improve learner comprehension at the sentence level; (b) lexical elaboration triggers incidental vocabulary acquisition while simplification does not; and (c) learners of higher proficiency benefit more from lexical elaboration in terms of the acquisition of word meanings. Background: ♦ Types of modification • Simplification: controlling the text targeted to L2 learners by removing unfamiliar linguistic items (e.g., unknown grammatical constructions and lexis) in order to enhance comprehension. • Elaboration: adding redundant information to the text through the use of repetition, paraphrases, and appositonals (Long, 1996, p. 422). (1) Baseline version: Everybody knows that Ken is diligent and kind to others. (2) Simplified version: Everybody knows that Ken is hardworking and kind to others. (3) Elaborated version: Everybody knows that Ken is diligent , or hardworking , and kind to others. (from Urano, 1998) ♦ Simplification, elaboration, and second language comprehension Table 1. Summary of the Studies on Simplification, Elaboration, and L2 Comprehension Study Brown (1985) elaborated elaborated >ns simplified >* >* baseline baseline Tsang (1987) simplified simplified >ns elaborated >* >* baseline baseline Yano et al. (1994) (inference items) simplified simplified elaborated elaborated >ns >* elaborated >* simplified >* >ns >* baseline baseline baseline baseline Chung (1995) simplified simplified >ns elaborated >* >ns baseline baseline Note : >* = statistically significant difference, >ns = non-significant difference